Hand tool comprising a dust suction device

ABSTRACT

The dust removal device comprises a fan ( 18 ), a dust collection receptacle ( 24 ), and a suction passage ( 28 ). The dust collection receptacle ( 24 ) equipped with a dust filter ( 26 ) is located in the path of air flow ( 34, 36 ) between the suction passage ( 28 ) and the fan ( 18 ). The dust is therefore filtered out of the air stream before it reaches the fan, which prevents dust-induced wear. It is also possible to use the same fan for engine cooling as well as dust removal.

BACKGROUND OF THE INVENTION

The present invention concerns a hand power tool with a dust removaldevice, comprising a fan driven by the motor of the hand power tool, adust collection receptacle, and a suction passage, whereby a path of airflow exists between the fan, the suction passage, and the dustcollection receptacle such that air is drawn through the suction passageby the fan and is conveyed into the suctioned dust collectionreceptacle, whereby the dust collection receptacle equipped with thedust filter is located in the oath of air flow between the suctionpassage and the fan.

A hand power tool with a dust removal device of this type was made knownin DE 196 53 330 A1. With this arrangement of the dust collectionreceptacle between the suction passage and the fan-unlike the dustremoval device made known, e.g., in DE 196 53 330 A1—the air filled withdust particles is not directed through the fan, because the fan can bedamaged by the dust, which comes in at a relatively high rate of speed.With the dust removal device made known in EP 579 964 A1, the fan servessimultaneously as fan to cool the motor of the hand power tool. Since itis not unlikely that the dust filter will become clogged, there is adanger that this could result in an inadequate amount of cooling airbeing directed past the motor.

The invention is based on the object of providing a hand power tool witha dust removal device of the type stated initially that can be realizedwith the least amount of technical effort possible, that is aswear-resistant as possible, and that always supplies the motor of thehand power tool with an adequate amount of cooling air.

SUMMARY OF THE INVENTION

The stated object is attained by providing an air passage for the fanthat supplies air to the fan when the fan produces an increased vacuumcaused by the dust filter becoming clogged. Even when the dust filter isclogged, the fan can then still draw enough air via an additional airpassage to cool the motor.

The path of air flow provided to cool the motor can be produced not onlyby directing the air drawn through the dust collection across the motorbefore it reaches the fan, but also by the fact that the fan blows theair drawn in through the suction passage and the dust collectionreceptacle past the motor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described hereinbelow with reference to theexemplary embodiments presented in the drawings.

FIG. 1 is a partial sectional view of a hand power tool with a firstvariant of a path of air flow that cools the motor,

FIG. 2 is a schematic representation of the mode of action of dustremoval and motor cooling according to the variant according to FIG. 1,

FIG. 3 is a partial sectional view of a hand power tool with a secondvariant of a path of air flow to cool the motor, and

FIG. 4 is a schematic representation of the mode of action of dustremoval and engine cooling according to the variant depicted in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a partial sectional view of a hand power tool 10, e.g., adrilling hammer. The invention described hereinbelow concerns any typeof hand power tool, however, that has a rotating drive and with whichdust is produced when an object is machined.

As one can see through the cut-out in FIG. 1, a motor 12 is located inthe hand power tool 10 that has a drive shaft 14 for a tool (not shown)mounted in a tool holder 16 of the hand power tool 10. A fan 18 ismounted on the drive shaft 14 that comprises a fan chamber 20 and aventilator 22 that is located therein and is coupled with the driveshaft 14.

A dust collection receptacle 24 with a dust bag 26 functioning as dustfilter is located on the outside of the power tool 10. A suction passage28 empties into the dust collection receptacle 24 and/or into the dustbag 26, which said suction passage extends into the vicinity of the toolmounted in the hand power tool 10 where dust is produced while the handpower tool 10 is operated. An air-conducting connection is producedbetween the dust collection receptacle 24 and the ventilator 22 of thefan 18 via a common opening 30 in the dust collection receptacle 24 andin the housing of the hand power tool 10, and via an opening 32 in thefan chamber 20 of the fan 18. A path of air flow is therefore producedto the fan chamber 20 via the suction passage 28 and the dust collectionreceptacle 24 equipped with a filter 26.

If the ventilator 22 is now started rotating when the hand power tool 10is operated and a vacuum is therefore produced in the fan chamber 20,the air filled with dust and generated at the site of the tool is drawnin through the suction passage 28 and into the dust collectionreceptacle 24, as indicated by the dashed arrow 34. The air flow passesthrough the dust bag 26, by way of which it is separated from the dustparticles, and finally reaches the fan chamber 20, as indicated by thedashed arrow 36. The suctioned air is blown out of the fan chamber 20through an opening 38 in another side of the fan chamber 20—as indicatedby the dashed arrow 40—and reaches the outside through one or more airslits 42 in the housing of the hand power tool 10.

In addition, an air stream directed past the motor 12—as indicated bythe dashed arrow 46—is drawn in through one or more openings 32, 44 inthe fan chamber 20, which said openings face the motor 12. This airstream 46 is drawn in from the outside through one or more air slits 48in the housing wall of the hand power tool 10. The air slit or air slits48 is/are positioned relative to the motor 12 in such a fashion that apath for air flow past the motor 12 results that ensures optimum coolingof the motor 12. The air drawn in past the motor 12 is also blown out ofthe fan chamber 20 to the outside via one or more openings 38 in theopposite side of the fan chamber 20 through the air slit(s) 42 in thehousing wall of the hand power tool 10. The fan 18 therefore performstwo functions simultaneously, i.e., dust removal and motor cooling.

The ventilator 22 in the fan chamber 20 can be installed directly on thedrive shaft 14 of the motor 12, or it can be coupled with the driveshaft via a gearset having a high gear ratio. The ventilator 22 couldtherefore be operated at a high rotational speed in order to obtain thegreatest suction power possible. The suction power can also be increasedby situating a plurality of ventilators in tandem.

In deviation from the exemplary embodiment presented in FIG. 1, in thecase of which the dust collection receptacle 24 is located outside thehand power tool 10, this dust collection receptacle can also beintegrated inside the hand power tool 10.

Passages having an appropriate structural design can be provided insidethe hand power tool to obtain a more targeted conductance of the airflows 36, 40, 46 and, therefore, a more effective intake and/ordischarge of air.

The schematic representation shown in FIG. 2 is provided to illustratethe individual paths of air flow that occur in the hand power tool 10according to FIG. 1. The individual blocks 12, 18, 24 represent themotor 12, the fan 18, and the dust collection receptacle 24 with thedust bag 26 located therein and serving as filter. The air flows 34, 36,42, 46 drawn in FIG. 1 have the same reference numerals in FIG. 2. FIG.2 shows clearly that two paths of air flow 36 and 46 enter the fan 18,whereby the one path of air flow 36 travels through the dust collectionreceptacle 24, and the other path of air flow 46 travels past the motor12.

FIGS. 3 and 4 show a further exemplary embodiment of a dust removaldevice that performs motor cooling simultaneously with and in additionto dust removal. The elements in FIGS. 3 and 4 that have the samesignificance and mode of action as elements in FIGS. 1 and 2 have beenlabelled with the same reference numerals as in FIGS. 1 and 2. Elementsthat are found in FIGS. 1 and 2 and that were already describedhereinabove will not be described once more with regard for FIGS. 3 and4. The exemplary embodiment presented in FIGS. 3 and 4 basically differsfrom the exemplary embodiment in FIGS. 1 and 2 in terms of a differentpath of air flow for cooling the motor 12.

The air flow that was drawn in via the suction passage 28 and cleaned ofdust by the dust bag 26 acting as filter travels through one or moreopenings 50 and reaches the fan chamber 20. The air is blown out of thefan chamber 20 through one or more openings 32, 44 in such a manner, infact, that this discharged air is directed past the motor 12 and travelsthrough one or more air slits 48 in the housing wall of the hand powertool 10 to reach the outside. This air stream, which leaves the fanchamber 20 and serves to cool the motor 12, is indicated in FIG. 3 by adashed arrow 52. In order to convert the suctioned air flow 36 into thecooling air flow 52, the opening 50 is located on the side of the fanchamber 20 opposite the motor 12 and the openings 32, 44.

The dust bag 26 can become so full of dust that the air flow 36 drawn inby the fan 18 is not sufficient to form a cooling air flow 52 that isgreat enough for the motor 12. An additional air passage 54 is providedfor this case, which said additional air passage empties into the fanchamber 20 via an opening 56. This opening 56 for the air passage 54 islocated on the same side as the opening 50 for the air flow 36 from thedust collection receptacle 24. The air passage 54 leads out of thehousing of the hand power tool 10 and forms an access for an air flow58, shown as a dashed arrow, from outside of the hand power tool 10 intothe fan chamber 20. The air flow 58 into the fan chamber 20 should notbe opened, however, until the other air flow 36 out of the dustcollection receptacle 24 has become too weak, which is expressed as anincrease in the vacuum in the fan chamber 20. A valve 60 is thereforeprovided in the air passage 54 that does not open and allow air 58 to bedrawn in until an increased vacuum occurs in the fan chamber 20. In thisfashion, adequate cooling of the motor 12 is possible even when the dustfilter is clogged.

The dual function of the fan 18, i.e., dust removal and motor cooling,can be illustrated once more with reference to the schematicillustration in FIG. 4. The same reference numerals are used in FIG. 4as for the corresponding elements and air flows shown in FIG. 3. FIG. 4illustrates that the air flow 36—directed through the dust collectionreceptacle 24 and cleaned of dust—is converted into an air flow 52 tocool the motor 12. The air flow 58 controlled by the valve 60 is alsoindicated in FIG. 4, which said air flow supplements or replaces the airflow 36 from the dust collection receptacle 24 when a certain vacuumoccurs in the fan chamber 20 that is caused by the dust bag 26 becomingclogged.

1. A hand power tool with a dust removal device, comprising a motor, afan driven by said motor and supplying cooling air to said motor, a dustcollection receptacle; a suction passage formed so that a path of airflow exists between said fan, said suction passage and said dustcollection receptacle such that air is drawn through said suctionpassage by said fan and the dust particles in a suctioned air stream areconveyed into said dust collection receptacle, said dust collectionreceptacle being provided with a dust filter located in the path of airflow between said suction passage and said fan; and an air passage forsaid fan supplying air to said fan when said fan produces an increasedvacuum caused by said dust filter becoming clogged.
 2. A hand poweredtool as defined in claim 1, wherein said fan blows out air drawn in viasaid suction passage and said dust collection receptacle past said motorvia a further path of air flow.
 3. A hand powered tool as defined inclaim 1; and further comprising a valve located in said air passage andopening when a vacuum is produced in said air passage.